Methods for printing images by depositing patterns of materials—inks or toners—on substrates are well known. These methods are generally fast, inexpensive and suitable for printing a very large number of copies of an image rapidly. Depending on the printing method, printing resolution may be as fine as ten or a few tens of microns. Photolithography methods for producing modern integrated circuitry are methods for depositing patterns of materials on substrates and typically provide pattern deposition resolutions that are better than a few tenths of a micron. However, these methods are extremely expensive, slow and complicated compared to printing methods.
Whereas pattern resolutions equal to and better than a few tenths of a micron are required for producing very fast integrated circuits, there are many applications for which substantially less resolution is sufficient. For example, for producing TV and flat panel displays, circuit manufacturing techniques having pattern resolutions of about 10 microns are often sufficient and for simple circuits, such as those used in toys, even lower resolution may be sufficient. Therefore, if printing techniques that are used to print images at resolutions of about ten microns or a few tens of microns can be adapted to print materials suitable for producing electronic components and display elements, circuitry, such as video displays, could be produced in large quantities at costs that are small fractions of current costs.
Different approaches for printing circuitry are under investigation and printing inks of various kinds suitable for, for example, screen, gravure, offset, electrostatic, ink-jet and micro-contact printing of circuit elements are under development.
U.S. Pat. No. 6,652,075, the disclosure of which is incorporated herein by reference, describes semiconducting inks suitable for ink-jet type printing or screen printing. The patent notes that the semiconducting inks may be produced by dispersing a semiconducting powder such as Si, Germanium or GaAs powder with n-type or p-type impurities in a binder.
U.S. Pat. No. 6,274,412, the disclosure of which is incorporated herein by reference, describes using printing techniques to manufacture an active matrix liquid crystal display (AMLCD). However, printing is limited in this disclosure to electrostatic printing of metal conductors for gate and data lines of the array and Indium Tin Oxide (ITO) pixel electrodes. Semiconducting components of thin film transistors (TFT) used to control the matrix are described as being produced by plasma enhanced chemical vapor deposition (PECVD).